1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member and a method of producing the electrophotographic photosensitive member, and a process cartridge and an electrophotographic apparatus each including the electrophotographic photosensitive member.
2. Description of the Related Art
An electrophotographic photosensitive member generally includes a support and a photosensitive layer formed on the support. In addition, an undercoat layer is often formed between the support and the photosensitive layer for the purpose of suppressing the injection of charge from the support toward the photosensitive layer to suppress the occurrence of an image defect such as a black spot.
In recent years, a charge generation substance having additionally high sensitivity has been used as a charge generation substance for the electrophotographic photosensitive member.
However, as the sensitivity of the charge generation substance rises, the amount of charge to be generated increases. Accordingly, a problem has arisen in that the charge is liable to remain in the photosensitive layer and hence a ghost is liable to occur. Specifically, the so-called positive ghost phenomenon, in which the density of only a portion irradiated with light at the time of forward rotation in an output image increases, is liable to occur.
To solve the problem, Japanese Patent Application Laid-Open No. 2010-122440, Japanese Patent Application Laid-Open No. 2007-148294, and Japanese Patent Application Laid-Open No. 2007-179031 each disclose a technology involving incorporating an electron transport substance into the undercoat layer. In addition, Japanese Patent Application Laid-Open No. 2007-148294 describes the following technology. When the electron transport substance is incorporated into the undercoat layer, the undercoat layer is cured so that the electron transport substance may not be eluted in a solvent in an application liquid for the photosensitive layer at the time of the formation of the layer above the undercoat layer (photosensitive layer).
A requirement for the quality of an electrophotographic image does not cease to become more and more sophisticated nowadays, and hence tolerance for the positive ghost has become markedly strict.
In addition, studies made by the inventors of the present invention have found that the technology disclosed in each of the above-mentioned documents is susceptible to improvement in terms of a suppressive effect on the positive ghost.